• Beardie Bliss

How Much UVB Does a Bearded Dragon Need?

Bearded dragons require about 8 to 12 hours of UVB light daily, usually during the day, so you should turn on the light first thing in the morning and turn it off in the evening. Since it helps with digestion, keep it on for at least one hour in the morning before feeding your beardie and one hour after dinner. If you forget to turn the UVB light off and on, set a timer to help you remember or get a light with a time.

Beardies do not require UVB light at night. In their natural habitat, it's dark at night, and temperatures come down. Not giving them UVB light at night reinforces their natural day-night cycle, mimicking these conditions to help them rest and sleep well.

The required daily amounts of heat and visible light also vary with the seasonal changes. For instance, 8 to 10 hours of UVB light is recommended during winter compared to 14 hours in summer.

What Happens if You Do Not Provide Adequate UVB Light?

Lack of adequate UVB light makes your beardie susceptible to certain diseases. They rely on UVB rays to synthesize Vitamin D, which is essential for calcium absorption. Therefore, underexposure can result in calcium deficiency leading to a condition known as metabolic bone disease.

If your bearded dragon is in the early development stages, calcium deficiency inhibits bone, muscular, and skeletal growth, which leads to weak limbs and difficulty with movement. On the other hand, adult bearded dragons may get weak.

Metabolic bone disease can also lead to organ damage and, in the worst-case, death. Other health issues that may result from underexposure include muscle wastage, deformities, paralysis, fragile bones, muscle twitching, soft jawbones, and dragging legs.

A bearded dragon should not go without UVB light for more than 48 hours. Otherwise, effects of underexposure begin to show immediately and get worse over time. Any damage and health issues caused by the deficiency can be difficult to reverse and treat and may become permanent.

Therefore, it is best to take measures to ensure UVB light is available throughout the day. Have an extra UVB lamp or a portable basking lamp at hand in case the one you have breaks or if the power goes out.

What is the Difference Between UVA and UVB?

Both UVB and UVA are forms of UV radiation, but they vary in strength and role in a beardie’s body.

UVB rays are medium-length rays. They are responsible for causing sunburns in people. However, desert lizards such as bearded dragons have thicker skin, so it is not harmful to them. It penetrates their bodies to help with vitamin D synthesis and calcium absorption.

On the other hand, UVA light has a longer wavelength. It causes wrinkles on human skin but is essential in bearded dragons as it helps digestion, reproduction, and other body functions.

Is it Possible to Overexpose a Bearded Dragon to UVB Light?

Yes, it is possible to overexpose a bearded dragon to UVB light. It can lead to adverse health effects, like hyperkeratosis, which is a chemical thickening of the skin; hypercalcemia or calcium build-up; and photo-kerato-conjunctivitis or sunburn on the eyes. A baby bearded dragon is more likely to suffer from overexposure than an adult. The key to preventing overexposure is keeping the UVB light level within the recommended range for baby and adult bearded dragons.

How Do You Know That Your Bearded is Getting the Right Amount of UVB light?

To determine if your beardie is getting the right amount of light, use a UV reader such as a solar meter. The UV index in the basking area should range between 2.5-and 7nm. Remember that UVB lights lose intensity over time, causing a decrease in the UVB light intensity. As such, you should keep a record of the UVB light index throughout the months to establish early on when there is a decline and change the bulb.

How far the UVB lamp radiates light depends on the wattage of the bulbs and if there are obstacles in the tank. The higher the wattage output, the higher the radiation distance. Most can radiate between 4 to 16 inches.

Most bearded dragon UVB bulbs have a wattage range between 80 to 160. If the tank is small, use a lower wattage and vice versa. Put bulbs with the highest wattage furthest from the basking spot. If the UVB bulb will be placed outside the tank, use one that has a higher wattage. The overall UV index inside the tank should not exceed 7nm.

What Types of UVB Light is Best for Bearded Dragons?

A new bearded dragon owner can find it difficult to choose the right UV light as there is a wide range in the market.

The most common types include coil bulbs and tube bulbs. Tube bulbs are more suitable for bearded dragons as they cover a wider area, ensuring a continuous supply of UVB light throughout the tank, not just in the basking spot.

On the other hand, coil UVB bulbs are not recommended. Aside from being unreliable, the rays are often too strong and concentrated in a pinpointed area of the bearded dragon tank. They are notorious for causing overexposure as their UV index is quite high. As such, coil UVB lights are not the most ideal for creating a natural-like and safe environment for bearded dragons.

The best UVB bulbs are specially made for bearded dragons, like the Zoo Med Reptisun. A 10 UVB output is ideal for bearded dragons. The secret to an easy UVB lighting setup is to buy a wired enclosure such as the Exo terra terrarium. A few come with a UVB light fitted in the terrarium hood.

When purchasing an ultraviolet light, you may also opt for a mercury vapor bulb. These bulbs are two-in-one as they emit both UVA and UVB rays. Some UVB fluorescent bulbs, such as the Zoo Med Reptisun also emit both types of UV radiation.

The latest entrant in UV lighting for bearded dragon care is the t5 bulb. It is one of the best UVB bulbs designed to overcome the limitation of fluorescent and coil UVB bulbs. The basking light emits a wild-like level of UVA and UVB rays, which are evenly distributed in the basking spot.

You can complement UVB and UVA bulbs with natural light by utilizing natural sun rays. Take your beardie outside for a walk or leave it outside a non-glass outdoor enclosure for a few hours. If you take your beardie out of the enclosure, keep in mind that the temperatures can rise too high, becoming fatal.


A UVB light is essential for the healthy living of your bearded dragon. Bearded dragons are originally from the Australian Desert. They are exposed to hot sun rays and bright light throughout the day in their natural habitat. Therefore, when setting up a vivarium for your beardie, you want to provide similar living conditions.


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